The present invention pertains to a mobile storage system including an anti-tip system for preventing tipping of the individual storage units. Generally, mobile storage systems fill the floor with movable side-by-side shelving units so that only a single aisle is provided in the entire storage area. An example of such a system is illustrated in U.S. Pat. No. 4,597,615 to Steger, and entitled STORAGE SYSTEM. Access to a particular unit is enabled by moving certain of the mobile shelving units to create an aisle adjacent the unit.
However, without the provision of an anti-tip arrangement, these mobile systems are subject to certain governmental safety restrictions. More specifically, OSHA regulations prohibit mobile storage units without an anti-tipping arrangement from exceeding a height-to-width ratio of 4 to 1. Accordingly, a typical two foot wide storage unit is limited to a height of eight feet. Furthermore, the California Seismic Safety Authority has ruled that all mobile storage systems installed in California must include anti-tip systems due to the additional hazards caused by earthquakes.
A common type of anti-tip system involves the use of upper bracing systems which fixedly mount to the ceiling, an adjacent wall, or on columns extending up from the floor. These bracing systems are coupled with the upper portions of the storage units to prohibit their tipping. One example of such a system is disclosed in copending application 07/129,683 filed Dec. 7, 1987, and entitled MOBILE SHELVING ANTI-TIP MECHANISM. This type of arrangement, however, is complex, expensive to fabricate and install, and produces an unsightly appearance. Moreover, if used in California, one must additionally verify that the ceiling, wall, or columns are sufficiently strong to resist the extra loads in the event of an earthquake.
Another type of anti-tip system is that manufactured and sold by Kardex, Inc., which includes specially designed carriages and carriage tracks. More particularly, the carriage tracks have raised outer edges which define narrow grooves with the floor. The carriages have cooperating L-shaped flanges which are received within the defined groove to prevent the shelving units from tipping over. Although, this arrangement eliminates many of the above mentioned shortcomings, such a system still includes several problems. More particularly, large stresses are generated within the track to offset the great moment forces invariably produced by the tipping. Accordingly, the carriage tracks must be extremely strong and rigid to sufficiently offset the risk of structural failure. Additionally, these anti-tip systems cannot be readily retrofitted to existing mobile shelving systems.